1. Field of the Invention
The invention relates to determining concentrations of molecules or atoms. More particularly, the invention relates to determining such concentrations using the ratio of two fluorescence signals.
2. Description of the Related Art
Concentrations of atoms or molecules in samples, such as biological samples, often need to be determined in clinical medicine and basic science applications. Some molecules can be detected by determining a level of fluorescence exhibited by the molecule when subjected to excitation. Other target molecules or atoms can be detected by binding different fluorescent molecules to the target molecules or atoms and detecting the fluorescence exhibited by the fluorescent molecules that are bound to the target molecule or atoms. The excitation energy is partially absorbed by the fluorescent molecules and is emitted, typically, as energy at a predetermined wavelength.
The fluorescence from a sample can be measured using a spectrometer. Typical spectrometers are large and expensive laboratory equipment that are usually only found in research facilities. Additionally, the results from the spectrometer need to be subjected to further signal processing in order to determine the concentration of a particular molecule or atom in the sample. More direct, inexpensive, and accessible instruments and methods are desired for detecting the concentrations of molecules and atoms in samples.